The invention relates to a towel dispenser, in particular a paper towel dispenser, comprising a housing in which a receiver such as a roller for the towel or several towels and an issuing device for said towel(s) is provided, with the issuing device being actuatable by a sensor activatable from the housing exterior. The invention further relates to a towel dispenser, in particular a paper towel dispenser, comprising a housing in which on the one hand the dispensed product, such as a paper roll, and on the other hand an issuing device are arranged.
Towel dispensers, in particular paper towel dispensers, whose issuing device reacts to a light-sensitive sensor are known. To prevent the sensor from reacting to light changes as caused by persons walking past, for example, the sensor in the known dispensing devices must be arranged on a lateral housing panel so that defined light conditions are assured. This however entails the drawback that persons wishing to operate the towel dispenser only find the laterally arranged sensor after a lengthy search. Also, these types of dispensing devices are often arranged with insufficient clearance from side walls, so that the amount of light is insufficient to dependably trigger operation.
A paper towel dispenser is described in U.S. Pat. No. 4,406,421. From its housing exterior, a lever is accessible via which rack and pinion inside the housing mesh such that a section of the paper towel is accessible via a issuing opening.
WO97/29671 describes an electrically actuatable paper towel dispenser that can be actuated by means of a photographic sensor.
In order to obtain liquid soap from a dispenser, in particular in the area of operating theaters, without the need to directly touch the dispenser, a capacitive sensor is used in accordance with DE 34 00 575 A1, the one electrode of which runs directly in the area of the liquid dispensing opening. The counter-electrode is formed by the space on which the person wishing to use the dispenser is standing.
The problem underlying the present invention is to develop a dispensing device of the type mentioned at the outset such that its operation is simplified and its dependability increased.
The problem is solved in accordance with the invention substantially in that the sensor is a capacitive sensor with a first two-dimensional and a second two-dimensional electrode arranged inside the housing and passing along at least one housing panel. In particular, it is provided that the first and the second electrode run in one plane or in two planes that are parallel or approximately parallel to a housing panel, in particular to the housing front panel. The electrodes should here have diverging two-dimensional extensions, in particular in the ratio of 1:5 to 1:20, in particular 1:10. Here an electrode can have a surface area of, for example, 8 cm2 and the other electrode a surface area of 0.8 cm2.
In particular, it is provided that the electrodes are at a distance from one another that in its width extension is equal to or less than the narrower electrode, which can also be described as strip-like. The electrodes themselves should have in the idle state, i.e. when the only dielectric outside the housing is air, a capacitance of approximately 1 pFxc2x10.25 pF. If the dielectric then changes because a hand approaches, the change in capacitance will trigger a signal that in its turn actuates the towel dispenser. The electrodes forming the capacitor and running in one plane or if necessary in two parallel planes, i.e. offset to one another, generate a virtually rectified field such that the capacitance is affected whenever a change is made in the dielectric distance up to approximately 30 mm from the surface of the towel dispenser housing by, for example, the approach of a hand. The capacitor formed by the electrodes running in one plane can be described as a folded-up panel-type capacitor.
The capacitive sensor generates in its surroundings an electrical field that is changed by the approach of a hand. The change is evaluated and triggers a pulse for actuating the issuing device. The dispensing device can therefore be used regardless of room-related light conditions or other environmental effects.
Also, for operating the issuing device it is only necessary for the electrical field running between the electrodes to be changed in some way to the necessary extent, for example by an approaching hand, without the need for contact with the housing at a certain spot or for the hand to remain in a certain area. Functioning is also assured in rooms in which heavy soiling or high relative humidity occurs.
In a particularly preferred embodiment, it is provided that the sensor on the housing front side is arranged directly behind a front side of the housing. The arrangement of the sensor on the front ensures easy operation of the dispensing device.
An arrangement on a different side or the alignment of one electrode each on a separate housing side is also possible, provided an effective and influencable field extends outside the housing.
In a further preferred embodiment of the dispensing device, it is provided that the front side of the housing has at least one visual element indicating a sensor field and/or a removal opening. It is provided here that the visual element on the front side of the housing is designed as at least two recesses running horizontally. The recesses are preferably designed as semicircular and relief-like grooves. It is also provided that the recesses divide the front of the housing in the ratio of the golden section.
Apart from indicating the removal opening or localizing the sensor field or sensor surface, the recesses increase the stiffness of the housing surface.
To rule out malfunctions of the dispensing device, the sensitivity of the capacitive sensor can be adjusted. For the simplest possible design of the sensor, it is proposed that it has a first and preferably two-dimensional electrode and a counter-electrode, both of which are arranged directly behind a front surface of the front side in order to generate an electrical field outside the housing.
To ensure a mains-independent operation of the dispensing device, the latter is equipped with a battery-powered drive device.
For simple maintenance and operation, a switch is arranged on the inside of the housing, using which the issuing device can be controlled when the housing is opened. Furthermore, a timer element is provided using which the operation time of the issuing device can be adjusted.
An integrated time-lag element is also provided to determine a time after which the issuing device can be operated again. As an overload protection for a motor operating the issuing device, the circuit array has an overcurrent protection.
In a mechanical embodiment of the dispensing device, a spring-loaded lever arm that can be operated from the front of the housing is provided that has a rack for operating the issuing device. The rack here follows a circular path at whose centerpoint is the rotary axis of the lever.
For the issue of paper towels in the form of paper rolls, but also in the form of single towels, it is provided that the issuing device comprises a puller roller and a pusher roller arranged opposite thereto, with the rack interacting with a gear arranged on the shaft of the puller roller. Here the gear is designed with sleeve freewheel.
In the electrical embodiment of the issuing device, a motor with an associated transmission is provided that engages in the gear arranged on the shaft of the puller roller. The motor is here controlled by the sensor-operated control unit.
In particular, with an embodiment as a paper towel dispenser, with the paper towels being rolled off a paper roll, a tear-off device is provided, the latter being arranged on the inside of the housing and not being accessible from the outside. In this the embodiment in accordance with the invention differs from the prior art, as in known devices the tear-off device is arranged on the front side of the housing, so that injuries are possible when pulling out or tearing off the paper towels.
Regardless of whether the dispensing device is operated electrically or mechanically, the housing has a number of advantages over the prior art. In a particularly preferred embodiment, it is provided that an upper side of the housing is angled about 8xc2x0 from the horizontal towards the beholder, so that rolling objects such as cigarettes cannot be rested on it.
Also, an intermediate field is provided between the upper side and the front side and angled towards the mounting wall. In addition, housing vision panels are arranged on at least one side wall for observing the items being dispensed. The housing is preferably made totally of plastic.
Further details, advantages and features of the invention are shown not only in the claims and in the features they containxe2x80x94singly and/or in combinationxe2x80x94but also in the following description of preferred embodiments shown in the drawing.